How does cbs sportsline allow Johan Santana to be simply dropped and picked up randomly. In my league's case, he was picked up by the team I am battling with in roto because he had a higher waiver priority than me. How does CBS not have him as an undroppable pleyer?

It is an option on CBS leagues, so I guess your league didn't select it. Very annoying to say the least in this case, but I've been burned the other way several times trying to drop a player who was out-for-the-year with injury but couldn't do so in the week I wanted due to him being an "undroppable" player. After an email to CBS, they would change the designation but normally after roster deadline.